One or more parameters of a patient may need to be monitored over a period of time to diagnose a condition of a patient, monitor changes of the condition of the patient, to determine the efficacy of a therapy provided to the patient, or for another medical reason. In one example, a medical system may measure one or more parameters relating to cardiac performance, such as heart rate, blood flow, stroke volume, blood pressure, cardiac output, blood oxygen saturation, location and/or size of various portions of the heart, or the like. The measured parameters may be used to diagnose or monitor a cardiac condition of the patient and/or to determine a course of treatment for the cardiac condition.